This invention relates to a workbook suited for the study of school subjects such as arithmetic, national language and foreign languages.
In a known workbook of this type, expected answer sections for given problems are left as blanks or are hidden to be unreadable in by a special manner such that the answer can be made to appear by a special adjustment when desired. That is to say, in such workbook attention has been paid only to how to hide the answer sections and how to effectively cause the answers to appear.
However, in the study of many school subjects, it is known to be effective not only to prepare an expected answer from the given problem, but also to prepare the problem from the given answer. For example, in case of the study of English words by a Japanese student, it is effective to learn the Japanese meaning from an English word with the latter being the problem and also to learn the English word from the Japanese meaning with the latter being problem. Likewise, in case of the study of the four rules of arithmetic, it is effective to calculate not only an expected answer from the given two numerals constituting the problem but also to calculate one numeral of the problem from the other numeral of the problem and the given numeral of the answer.
Notwithstanding the above-mentioned study effect of preparing an expected answer from the given problem and also the problem from the given answer, the known workbook set forth above has been adapted only for the study of preparing the expected answer from the given problem, so that above discussed higher study effect could not be achieved.